1. Field of the Invention
The present invention relates to a developing apparatus which can be used in an image forming apparatus.
Here, the image forming apparatus uses an electrophotographic image forming process to form an image on a recording material, and examples thereof include an electrophotographic copying machine, an electrophotographic printer (LED printer, laser beam printer, and the like), an electrophotographic facsimile machine, an electrophotographic word processor, and the like.
2. Related Background Art
In an electrophotographic image forming apparatus, for example, a printer, selective exposure is performed to an image bearing member (photosensitive drum) uniformly charged by a charging device to form a latent image, the latent image is visualized with a developer (toner) by a developing device, and the image by the developer is transferred to a recording material to perform image recording. Subsequently, after the transfer, the developer remaining on the image bearing member is removed with a cleaning blade, the developer is stored in a cleaner container, and the next development is performed by the image bearing member with a cleaned surface.
In recent years, an apparatus has been turned to practical use in which the image bearing member, charging device, developing device, cleaning portion, waste toner box, and the like are integrally structured into a cartridge, and a user mounts the cartridge onto a main body of the apparatus (an apparatus main body), so that component replacement of the developer image bearing member is realized, and maintenance is facilitated.
Furthermore, when a life of the image bearing member is extended and the number of printable sheets is increased, the developing device whose supplying ability is limited is used as an independent unit. The apparatus is divided into the developing unit and a drum unit in which the image bearing member as image forming process means, charging device and cleaning portion are integral. In the same manner as a process cartridge, the mounting onto the apparatus main body and the maintenance are facilitated. Additionally, the apparatus is increasingly used in accordance with the life of each main component. Waste toner generated in the drum unit by cleaning is stored in a cleaning container which has a capacity to sufficiently contain the toner during the image bearing member's life, and removed at the time of drum unit replacement.
In recent years, a color electrophotographic image forming apparatus which can form color images is increasingly demanded. For example, a constitution is known in which four-color developing apparatuses are all arranged in a rotary (e.g., U.S. Pat. No. 4,707,108, U.S. Pat. No. 5,040,031, and the like).
The constitution is very effective for forming the color images.
On the other hand, a color electrophotographic image forming apparatus for application to a future network needs to handle a large amount of high-speed outputs, whether a color document can be outputted or not. Moreover, it is desirable to reduce a cost per page like in a monochromatic electrophotographic image forming apparatus.
To meet the demand, life lengthening of consumable for use in the apparatus (e.g., the developing unit and the drum unit as the image bearing unit, the process cartridge in which the developing unit and the image bearing unit are integral, and the like) needs to be intended.
For this purpose, for example, the developing unit needs to be provided with a large-capacity developer containing portion which contains a large amount of developer.
Moreover, in order to handle the high-speed output, developer supply needs to be increased. For example, an opening (opening portion) formed in the developer containing portion of the developing unit has to be enlarged in such a manner that a stable developer supply can be performed.
Then, a width of a sheet-shaped unsealable seal member to seal the opening is also increased.
However, when the developer containing portion is enlarged, a weight of the developer is proportionally enlarged. Then, a surface pressure of the developer to the unsealable seal member to seal the opening of the developer containing portion is also enlarged.
In this state, for example, when the developing unit is dropped, a large powder pressure is applied to the unsealable seal member, a part of the unsealable seal member is broken, and the developer may leak.
When the developer leaks to the outside of the developing unit, during operation a user's body is probably made dirty. Moreover, when the developing unit itself is very dirty, it must be replaced with a new one.